Changes in Joint Power and Energetics during a Sport-Specific Jumping Fatigue Protocol

Kinematic and kinetic changes in the lower extremities occur as an athlete becomes fatigued during vertical jumping; however, the specifics of these changes are not well-understood. Therefore, the purpose of this study was to quantify the influence of a sport-specific, vertical jumping fatigue protocol on the biomechanics of the ankle, knee, and hip joint. Twenty male varsity athletes performed repetitive standing countermovement squat jumps every 20 s until fatigued (vertical jump and reach height decreased to 88% of their maximum height for three consecutive jumps). The kinematics and kinetics of their lower extremities (ankle, knee, and hip) were quantified, and the ankle, knee, and hip joint's moments, angular velocity, and joint power were compared. The participants performed an average of 175 jumps before they were classified as being fatigued. When they became fatigued, the peak power of the ankle and hip joints were substantially reduced due to a decrease in the angular velocity at both joints. Ankle and hip joint moments were unchanged. Peak power at the knee joint was also unchanged over the course of the jumping protocol. To maintain vertical jumping performance over the course of a game or to delay the influence of fatigue, training should be targeted at maintaining the angular velocity of the ankle and hip joints.